Many different optical systems have been devised for enabling the simultaneous observation of an optical signal or scene in more than one wavelength region. For example, Lareau and Partynski describe a dual image reconnaissance camera capable of operating in the visible or infrared spectral bands or in both simultaneously. The camera functions by collecting an image with a single objective lens and re-imaging this image into two separate optical channels through a CaFl beam divider/prism. Each of the channels contains appropriate optics, including a wafer-scale focal plane array for capturing images in the appropriate region of the optical spectrum (Lareau and Partynski, Dual band framing cameras: technology and status, Proceedings of SPIE, Vol. 4127 (2000) 148-150).
U.S. Pat. No. 5,512,750 discloses another method of producing simultaneous images in two different wavelength regions. In this case, sensors producing simultaneous, superimposed, two-dimensional images in two IR bands with the dual band detector arrays monolithically integrated upon a common substrate are described. Here the incoming infrared image is viewed simultaneously in the medium and long wave infrared bands.
Another useful property of optical systems is the ability to switch an image from one optical track to another, enabling the image to be viewed at different locations, with different types of detectors, and even in different spectral regions, according to the decision of the operator of the system. A common method of accomplishing this is to make use of switching mirrors that are moved in and out of the optical path to direct the beam to different directions. Typical optical arrangements of this sort are described in: Lloyd, J M, Thermal Imaging Systems, Plenum Press, New York and London, 1982, p.256.
Although it would be advantageous for many applications to be able to provide optical systems with both properties, i.e. the ability to simultaneously observe the same image in different wavelength regions and also to switch at least one of the images between different detectors, to date optical systems containing both of these properties do not exist. Such a combination would be especially useful, for example, for a system comprising a video camera combined with a laser range finder and a laser designator receiver or for an optical communication system in which fiber optical components replace the optical detectors.
It is therefore a purpose of the present invention to provide an optical system that receives an incoming beam of electromagnetic radiation, divides the incoming beam into a transmitted beam, containing a part of the wavelength band, and a reflected beam, containing the remainder of the wavelengths, transfers the transmitted beam continuously to a detector, and is further capable of switching the reflected beam between any one of two or more detectors.
It is a further purpose of the present invention to provide a communication system that receives an incoming signal, divides the incoming signal into a transmitted signal, containing a part of the wavelength band, and a reflected signal, containing the remainder of the wavelengths, transfers the transmitted signal continuously to fiber optical elements, and is further capable of switching the reflected signal between any one of two or more fiber optical elements.
Further purposes and advantages of this invention will appear as the description proceeds.